Haffman main

note
    description: "Haffman application root class"
    date: "$Date$"
    revision: "$Revision$"

class
    APPLICATION

inherit
    ARGUMENTS

create
    make

feature {NONE} -- Initialization

arr:LINKED_PRIORITY_QUEUE[PAIR]
freq:ARRAY[INTEGER]
    make
            -- Run application.
    local
        s:STRING
        t:PAIR
        do
            create freq.make_filled (0, 0, 255)
            s:="abcdff"
            set_freq(s)
            make_tree
            t:=arr.item
            generate_codes(t, "")
        end

    generate_codes(ch:PAIR; code:STRING)
    do
        if ch.char /= -1 then
            print(ch.char.to_character_8.out + " = " + code + "%N")
        end

        if attached ch.left as l then
            generate_codes (l, code + "0")
        end

        if attached ch.right as r then
            generate_codes (r, code + "1")
        end
    end

    set_freq(s:STRING)
    do
        across
                s as char
            loop
                freq[char.item.code] := freq[char.item.code] + 1
            end
    end

    make_tree
    local
        t,t1,t2:PAIR
        i:INTEGER
    do
        create arr.make
        from
            i:=0
        until
            i>255
        loop
            if freq[i] > 0 then
                create t.make (i, freq[i])
                arr.extend (t)
            end
            i:= i + 1
        end



        from
        until
            arr.count = 1
        loop
            t := arr.item.twin
            arr.remove
            t1 := arr.item.twin
            arr.remove
            create t2.make (-1, t.cnt+t1.cnt)
            t2.set_left (t.char, t.cnt)
            t2.set_right (t1.char, t1.cnt)
            arr.extend (t2.twin)
        end
    end

end